Three-dimensional thermoelectric device based on double-sided silk-screen printing and preparation method thereof

Abstract

The invention discloses a three-dimensional thermoelectric device based on double-sided silk-screen printing and a preparation method thereof, and belongs to the technical field of new energy devices, the three-dimensional thermoelectric device is obtained by folding a two-dimensional layout structure for multiple times, and the two-dimensional layout structure is a double-sided structure prepared on a substrate by using a silk-screen printing process. Each face structure comprises a bottom electrode layer, an N-type thermoelectric material layer, a P-type thermoelectric material layer and a top electrode layer which are of an array structure in sequence. The N-type thermoelectric supporting legs and the P-type thermoelectric supporting legs are alternately arranged, and the N-type thermoelectric supporting legs, the P-type thermoelectric supporting legs and the top-layer electrode unit all have overlapping areas with the bottom-layer electrode unit; the two-dimensional layout structure is folded into a three-dimensional thermoelectric device through multiple folding, three-dimensional collection of heat flow can be achieved, the limited substrate area is fully utilized, and the three-dimensional thermoelectric device has the advantages of being high in output power density, compact in structure, high in integration degree and small in occupied area and is particularly suitable for wearable scenes.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy devices, and in particular relates to a three-dimensional thermoelectric device based on double-sided screen printing and a preparation method thereof. Background Art

[0002] Thermoelectric devices convert industrial and domestic waste heat into electrical energy through the Seebeck effect. They have the advantages of not requiring mechanical input, not being restricted by light, and not requiring user intervention. Therefore, they are usually more stable and reliable and are an effective solution to alleviate energy and environmental problems.

[0003] In recent years, the rapid development of micro-nano manufacturing technology has promoted the development of electronic products towards miniaturization, multi-function and integration, and the power consumption has also dropped from milliwatts (mW) to microwatts (μW) and even to nanowatts (nW). Even if the conversion efficiency is less than 1%, the temperature difference between the human body and the environment is enough to drive thermoelectric devices to generate electricity and power a variety of electronic devices. Thermoelectric devices are expected to replace batteries as efficient power sources in wearable scenarios, avoiding application limitations caused by frequent charging, regular maintenance and replacement, and environmental pollution.

[0004] Many flexible film-based thermoelectric devices are designed as planar structures, with thermoelectric legs and metal interconnects placed on a flexible substrate to collect in-plane heat flow. However, this configuration for collecting in-plane heat flow is inconsistent with the direction of heat flow between the human body and the environment (i.e., the direction of heat flow perpendicular to the plane), and cannot effectively collect body heat. At the same time, the temperature difference between body temperature and the environment is small, and the output of thermoelectric devices is usually low.

[0005] Therefore, it is necessary to propose a highly integrated thermoelectric device that can collect heat flow between the human body and the environment to provide new ideas for wearable scenarios. Summary of the invention

[0006] In response to the problem that existing planar thermoelectric devices cannot effectively collect body heat, the present invention provides a three-dimensional thermoelectric device based on double-sided screen printing and a preparation method thereof. Multiple folding is used to obtain a highly integrated three-dimensional thermoelectric device to achieve three-dimensional collection of heat flow, which is particularly suitable for wearable scenarios.

[0007] The technical solution adopted by the present invention is as follows:

[0008] A three-dimensional thermoelectric device based on double-sided screen printing is obtained by folding a two-dimensional layout structure multiple times; the two-dimensional layout structure is a double-sided structure prepared by a screen printing process on a substrate, the structures of both sides are the same, and each side structure includes a bottom electrode layer, an N-type thermoelectric material layer, a P-type thermoelectric material layer and a top electrode layer in sequence;

[0009] The bottom electrode layer is an array of 4m×2n isolated bottom electrode units; the N-type thermoelectric material layer is an array of m×n isolated N-type thermoelectric legs; the P-type thermoelectric material layer is an array of m×n isolated P-type thermoelectric legs; the top electrode layer is an array of (2m+1)×2n isolated top electrode units;

[0010] The N-type thermoelectric legs and the P-type thermoelectric legs are alternately arranged to form a 2m×2n double-grid structure array; in each row of the double-grid structure array, the two sides of the N-type thermoelectric legs have overlapping regions with two bottom electrode units respectively, and the two sides of the P-type thermoelectric legs have overlapping regions with two bottom electrode units respectively, and the top electrode unit is located in the area between the adjacent N-type thermoelectric legs and the P-type thermoelectric legs, and has an overlapping region with the N-type thermoelectric legs and the P-type thermoelectric legs, and has an overlapping region with the bottom electrode unit overlapping one side of the N-type thermoelectric legs, and has an overlapping region with the bottom electrode unit overlapping one side of the P-type thermoelectric legs, so that the adjacent N-type thermoelectric legs and P-type thermoelectric legs in each row are electrically interconnected;

[0011] The top electrode units in adjacent rows in the top electrode layer are connected end to end, thereby forming an electrical interconnection region of a serpentine bending structure in each side structure;

[0012] By folding multiple times, the two-dimensional layout structure is folded into a three-dimensional thermoelectric device formed by stacking 2m×2n layers of thermoelectric units, and each layer of thermoelectric units includes an N-type thermoelectric leg or a P-type thermoelectric leg.

[0013] Furthermore, the substrate is a polyimide film with a thickness of 15 to 50 μm; and the material of the bottom electrode layer and the top electrode layer is silver.

[0014] Furthermore, electrical interconnection of the double-sided structure is achieved by providing through holes in the top electrode layer.

[0015] Furthermore, during the multiple folding processes, polyimide films are introduced to insulate adjacent layers of thermoelectric units.

[0016] Furthermore, by changing the area of ​​the overlapping region between the N-type thermoelectric leg and the bottom electrode unit, as well as the area of ​​the overlapping region between the P-type thermoelectric leg and the bottom electrode unit, the contact resistance between the bottom electrode layer and the N-type thermoelectric material layer and the P-type thermoelectric material layer is adjusted, thereby adjusting the internal resistance of the three-dimensional thermoelectric device.

[0017] Furthermore, m and n are both positive integers.

[0018] The method for preparing a three-dimensional thermoelectric device based on double-sided screen printing comprises the following steps:

[0019] Step 1, preparing a thermoelectric ink base liquid, and preparing an N-type thermoelectric ink and a P-type thermoelectric ink based on the thermoelectric ink base liquid;

[0020] Step 2, pre-drilling through holes on the substrate;

[0021] Step 3: placing screens with bottom electrode unit patterns on both sides of the substrate, and printing conductive silver paste on both sides of the substrate using a screen printing process, and obtaining a bottom electrode layer after pre-curing;

[0022] Step 4: Place a screen with a P-type thermoelectric leg pattern on both sides of the substrate treated in step 3, and use a screen printing process to print a P-type thermoelectric ink on the bottom electrode layer, and obtain a P-type thermoelectric material layer after pre-curing;

[0023] Step 5, placing screens with N-type thermoelectric leg patterns on both sides of the substrate treated in step 4, and printing N-type thermoelectric ink on the bottom electrode layer using a screen printing process, and obtaining an N-type thermoelectric material layer after pre-curing;

[0024] Step 6, heat-treating the substrate processed in step 5, and then placing screens with top electrode unit patterns on both sides of the substrate, and printing stretchable silver paste on both sides of the substrate using a screen printing process, and obtaining a top electrode layer after pre-curing, thereby obtaining a two-dimensional layout structure;

[0025] Step 7: Partially encapsulate the two-dimensional layout structure using a base material, and fold the encapsulated two-dimensional layout structure into a three-dimensional layered structure through multiple folding, thereby obtaining a three-dimensional thermoelectric device based on double-sided screen printing.

[0026] Furthermore, a specific process of the multiple folding is:

[0027] First, the gaps between adjacent rows in the two-dimensional layout structure are used as creases, and each row is folded in the same direction to form a long strip structure; then, the midline of the top electrode unit in the long strip structure is used as a crease, and each thermoelectric unit is folded in different directions to form a three-dimensional layered structure.

[0028] Furthermore, another specific process of the multiple folding is:

[0029] First, the gaps between adjacent rows in the two-dimensional layout structure are partially cut to ensure that the adjacent rows are connected end to end; then, starting from the first row, each thermoelectric unit is folded in half in different directions with the midline of the top electrode unit as the crease to form a three-dimensional layered structure unit; the three-dimensional layered structure unit of the first row is folded to the second row, and the thermoelectric units of the second row are folded in half in different directions until all rows of thermoelectric units are folded in half to form a three-dimensional layered structure.

[0030] Furthermore, the three-dimensional thermoelectric device includes a hot end and a cold end. Specifically, the fold of the top electrode unit on the same side of each layer of thermoelectric units is the hot end, and the fold of the top electrode unit on the opposite side is the cold end.

[0031] Furthermore, the thermoelectric ink base liquid is obtained by mixing a catalyst, a binder and a curing agent in a mass percentage of 1: (50-60): (40-50).

[0032] Furthermore, the N-type thermoelectric ink is obtained by mixing a thermoelectric ink base liquid with an N-type thermoelectric powder in a mass percentage of 1: (4.5-5.4).

[0033] Furthermore, the P-type thermoelectric ink is obtained by mixing a thermoelectric ink base liquid with a P-type thermoelectric powder in a mass percentage of 1: (5.5-6.5).

[0034] Furthermore, the heat treatment conditions in step 6 are: heating at 320-380° C. for 3.5-4.5 hours in a nitrogen or rare gas environment.

[0035] Furthermore, the pre-curing conditions of the conductive silver paste and the stretchable silver paste are: drying at 120-150° C. for 10-30 min.

[0036] Furthermore, the pre-curing conditions of the N-type thermoelectric ink and the P-type thermoelectric ink are: drying at 90 to 120° C. for 30 to 60 minutes.

[0037] Furthermore, in the multi-layer screen printing process of steps 3 to 6, positioning is performed by setting alignment marks.

[0038] The beneficial effects of the present invention are:

[0039] 1. The present invention proposes a three-dimensional thermoelectric device based on double-sided screen printing and a preparation method thereof. The two-dimensional layout structure obtained by screen printing is folded into a three-dimensional thermoelectric device by multiple folding, which can realize three-dimensional collection of heat flow, and is particularly suitable for wearable scenarios, and is used for heat flow collection between the human body and the environment; in order to make full use of the limited substrate area, screen printing is performed on both sides of the substrate, and through-hole electrical interconnection is used to connect all thermoelectric units in series to achieve an increase in output power; therefore, the three-dimensional thermoelectric device of the present invention has the advantages of high output power density, compact structure, high integration, and small occupied area;

[0040] 2. The three-dimensional thermoelectric device of the present invention is prepared by screen printing technology, which has the characteristics of low cost and easy large-scale production;

[0041] 3. The present invention performs joint heat treatment on the bottom electrode layer, N-type thermoelectric material layer and P-type thermoelectric material layer, which helps to reduce the contact resistance between the bottom electrode layer and the N-type thermoelectric material layer and the P-type thermoelectric material layer, and adjusts the internal resistance of the three-dimensional thermoelectric device by reasonably designing the overlapping area between the N-type thermoelectric leg and the bottom electrode unit, as well as the overlapping area between the P-type thermoelectric leg and the bottom electrode unit, so as to improve the output power density of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the principle of a three-dimensional thermoelectric device based on double-sided screen printing proposed in Example 1 of the present invention;

[0043] Figure 2 Schematic diagram of a double-sided multi-layer printing structure of a two-dimensional layout structure in Example 1 of the present invention;

[0044] Figure 3 is a schematic diagram of the multiple folding technology proposed in Example 2 of the present invention;

[0045] Figure 4 1 is a step-by-step schematic diagram of the preparation process of the two-dimensional layout structure in Example 2 of the present invention; wherein (a) is step 2; (b) is step 3; (c) is step 4; (d) is step 5; (e) is step 6; (f) is step 7;

[0046] Figure 5 Schematic diagram of the two-dimensional layout structure after packaging in Example 2 of the present invention; wherein (a) is the front side; (b) is the back side;

[0047] Figure 6 is a schematic diagram of the long strip structure in Example 2 of the present invention;

[0048] Figure 7 is a schematic diagram of a three-dimensional layered structure in Example 2 of the present invention;

[0049] Figure 8 is a relationship curve between the open circuit voltage, open circuit power and temperature difference of the three-dimensional thermoelectric device based on double-sided screen printing in Example 3 of the present invention;

[0050] Fig. 9 is a schematic diagram of the multiple folding technology proposed in Example 4 of the present invention;

[0051] The descriptions of the symbols in the accompanying drawings are as follows:

[0052] A0 is a polyimide substrate, A1-1 is a front bottom silver electrode layer, A1-2 is a front N-type thermoelectric material layer, A1-3 is a front P-type thermoelectric material layer, A1-4 is a front top silver electrode layer, A2-1 is a back bottom silver electrode layer, A2-2 is a back N-type thermoelectric material layer, A2-3 is a back P-type thermoelectric material layer, and A2-4 is a back top silver electrode layer. DETAILED DESCRIPTION

[0053] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Although limited embodiments are described below, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0054] Example 1

[0055] This embodiment provides a three-dimensional thermoelectric device based on double-sided screen printing, such as Figure 1 As shown, it is obtained by folding the two-dimensional layout structure multiple times, with one side of the three-dimensional thermoelectric device as the hot end and the other side as the cold end.

[0056] The two-dimensional layout structure is a double-sided structure prepared by screen printing on a substrate, the structures of both sides are the same, and each side structure includes a bottom electrode layer, an N-type thermoelectric material layer, a P-type thermoelectric material layer and a top electrode layer in sequence.

[0057] In this embodiment, a 15 μm thick polyimide film is used as the substrate material, and the materials of the bottom electrode layer and the top electrode layer are silver. Figure 2 As shown, it is composed of a front top silver electrode layer A1-4, a front P-type thermoelectric material layer A1-3, a front N-type thermoelectric material layer A1-2, a front bottom silver electrode layer A1-1, a polyimide substrate A0, a back bottom silver electrode layer A2-1, a back N-type thermoelectric material layer A2-2, a back P-type thermoelectric material layer A2-3 and a back top silver electrode layer A2-4.

[0058] The bottom electrode layer is an array composed of 4m×2n isolated bottom electrode units; the N-type thermoelectric material layer is an array composed of m×n isolated N-type thermoelectric legs; the P-type thermoelectric material layer is an array composed of m×n isolated P-type thermoelectric legs; the top electrode layer is an array composed of (2m+1)×2n isolated top electrode units.

[0059] In this embodiment, m and n are 6 and 3 respectively; the size of the two-dimensional layout structure is 180.5mm×75mm; the size of each bottom electrode unit is 10mm×1.25mm; the size of each N-type thermoelectric leg and each P-type thermoelectric leg is 10.5mm×10mm, and the spacing between adjacent N-type thermoelectric legs and P-type thermoelectric legs is 4mm; the size of each top electrode unit is 10mm×6.5mm.

[0060] The N-type thermoelectric legs and the P-type thermoelectric legs are alternately arranged to form a 2m×2n double-grid structure array; in each row of the double-grid structure array, there are overlapping areas on both sides of the N-type thermoelectric legs and the two bottom electrode units, and there are overlapping areas on both sides of the P-type thermoelectric legs and the two bottom electrode units, and the sizes of the two overlapping areas are both 10mm×0.5mm; the top electrode unit is located in the area between the adjacent N-type thermoelectric legs and the P-type thermoelectric legs, and there is an overlapping area with the N-type thermoelectric legs and the P-type thermoelectric legs, as well as an overlapping area with the bottom electrode unit overlapping one side of the N-type thermoelectric leg, and an overlapping area with the bottom electrode unit overlapping one side of the P-type thermoelectric leg, so that the adjacent N-type thermoelectric legs and P-type thermoelectric legs in each row are electrically interconnected; wherein, the size of the overlapping area between the top electrode unit and a single bottom electrode unit is 10mm×0.75mm.

[0061] The top electrode units in adjacent rows in the top electrode layer are connected head to tail, thereby forming an electrical interconnection region of a serpentine bending structure in each side structure. The electrical interconnection of the double-sided structure is achieved by setting through holes in the top electrode layer.

[0062] Through multiple folding, the two-dimensional layout structure is folded into a three-dimensional thermoelectric device formed by stacking 2m×2n layers of thermoelectric units, each layer of thermoelectric units contains an N-type thermoelectric leg or a P-type thermoelectric leg. In the multiple folding process, the interlayer insulation of adjacent layers of thermoelectric units is achieved by introducing polyimide films.

[0063] Based on the Seebeck effect, the current inside the N-type thermoelectric leg flows from the cold end to the hot end, and the current inside the P-type thermoelectric leg flows from the hot end to the cold end. Figure 1 The arrows on the N-type thermoelectric leg and the P-type thermoelectric leg represent the current flow direction when the temperature gradient shown in the figure is applied. After the three-dimensional thermoelectric device is formed by multiple folding technology and a heat source is applied to it, a continuous current will be formed inside the three-dimensional thermoelectric device.

[0064] Example 2

[0065] This embodiment provides a method for preparing a three-dimensional thermoelectric device based on double-sided screen printing as described in Example 1. The process is as follows: Figure 4 As shown, the specific steps include:

[0066] Step 1, mixing a catalyst, an adhesive, and a curing agent in a mass percentage of 1:60.4:38.6 to obtain a thermoelectric ink base liquid; wherein the catalyst is an amine catalyst or an imidazole catalyst; the adhesive is a variety of epoxy resins; the curing agent is an aromatic amine, dicyandiamide, a resol phenolic resin or anhydride, etc.; in this embodiment, the catalyst is specifically 1-cyanoethyl-2-ethyl-4-methylimidazole, the adhesive is specifically a mixture of bisphenol F epoxy resin and polypropylene glycol diglycidyl ether in a mass ratio of 1:1.2, and the curing agent is specifically methyl hexahydrophthalic anhydride;

[0067] Step 2: N-type thermoelectric powder and P-type thermoelectric powder are mixed with the base liquid obtained in step 1, wherein the mass ratio of N-type thermoelectric powder to the base liquid of thermoelectric ink is 5:1, and the mass ratio of P-type thermoelectric powder to the base liquid of thermoelectric ink is 6:1, and an electric stirrer is used to stir at a speed of 1000 r / min to obtain N-type thermoelectric ink and P-type thermoelectric ink; in this embodiment, the N-type thermoelectric powder is specifically made of Bi 2 Te 2.7 Se 0.3 , P-type thermoelectric powder specifically uses Sb 2 Te 3 ;

[0068] Step 3: Figure 4 As shown in (a), a through hole is previously punched in a polyimide film having a thickness of 15 μm;

[0069] Step 4: Figure 4 As shown in (b), a 100-mesh screen is used to print conductive silver paste on both sides of the polyimide film treated in step 3, and then the film is placed in a blast drying oven for drying at a temperature of 150°C for 10 minutes to obtain a bottom electrode layer;

[0070] Step 5: Figure 4 As shown in (c), a 100-mesh screen is used to print P-type thermoelectric ink on both sides of the polyimide film treated in step 4 to form a P-type thermoelectric leg array. The overlapping area between each bottom electrode unit and the P-type thermoelectric leg is 10 mm × 0.5 mm. The film is then placed in a blast drying oven for drying at a temperature of 120°C for 30 min to obtain a P-type thermoelectric material layer.

[0071] Step 6: Figure 4 As shown in (d), a 100-mesh screen is used to print N-type thermoelectric ink on both sides of the polyimide film treated in step 5 to form an N-type thermoelectric leg array. The overlapping area between each bottom electrode unit and the N-type thermoelectric leg is 10 mm × 0.5 mm. The film is then placed in a blast drying oven for drying at a temperature of 120°C for 30 min to obtain an N-type thermoelectric material layer.

[0072] Step 7: Figure 4 As shown in (e), the polyimide film treated in step 6 is placed in a muffle furnace for heat treatment, first evacuated, then introduced with pure nitrogen, and the above operation is repeated 3 times to ensure that the air in the oven is exhausted and a nitrogen environment is formed; the temperature is maintained at 350°C and the heat treatment is maintained for 4 hours, so that the printed P-type thermoelectric legs and N-type thermoelectric legs have good conductivity and thermoelectric properties;

[0073] Step 8: Figure 4 As shown in (f), a 300-mesh screen is used to print a stretchable silver paste on both sides of the polyimide film treated in step 7, and the overlapping area between each top electrode unit and the bottom electrode unit is 10 mm×0.75 mm. Then, the film is placed in a blast drying oven for drying at a temperature of 150°C for 10 min to obtain a top electrode layer, and then a two-dimensional layout structure is obtained. The through hole drilled in step 3 is located in the top electrode unit of the first row and the first column in the two-dimensional layout structure.

[0074] Step 9: Figure 5 As shown, additional polyimide tape is used to partially encapsulate the two-dimensional layout structure, specifically, one side of the two-dimensional layout structure is fully encapsulated, and the other side is only encapsulated with the last row to ensure insulation during the folding process;

[0075] Step 10: Figure 3 The multiple folding technology shown folds the packaged two-dimensional layout structure into a three-dimensional layered structure, thereby obtaining a three-dimensional thermoelectric device based on double-sided screen printing, specifically:

[0076] like Figure 6 As shown, the gaps between adjacent rows in the two-dimensional layout structure are used as creases, and each row is rolled up in the same direction to form a long strip structure; Figure 7 As shown in the figure, with the midline of the top electrode unit in the long strip structure as the fold, each thermoelectric unit is folded in two directions to form a three-dimensional layered structure with a volume of 2.2425cm 3 .

[0077] Example 3

[0078] In this embodiment, the following performance tests are performed on the three-dimensional thermoelectric device based on double-sided screen printing prepared in Example 2:

[0079] 1. Test method:

[0080] In this embodiment, an electrochemical workstation is used for testing. Specifically, a heating platform and a semiconductor refrigeration sheet are used as the controllable heat source and cold source of the three-dimensional thermoelectric device, respectively. A dual-input K-type thermometer (GM1312) is used to measure the temperature changes at the hot and cold ends of the three-dimensional thermoelectric device, and the real-time temperature difference is read. When the temperature difference reaches the required test value of 50°C, the open circuit voltage of the three-dimensional thermoelectric device at this time is recorded and input into the electrochemical workstation. The electrochemical workstation applies different currents to the three-dimensional thermoelectric device, specifically to the front and back sides of the first layer of thermoelectric units or the last layer of thermoelectric units in the three-dimensional layered structure, such as Figure 5 The two-dimensional layout structure shown shows the direction of the current in the three-dimensional thermoelectric device. It can be seen that after the current flows through all the thermoelectric units on both sides, the output voltage and power of the three-dimensional thermoelectric device under different load conditions are obtained.

[0081] 2. Test results:

[0082] The relationship curve between the open circuit voltage, open circuit power and temperature difference of the three-dimensional thermoelectric device based on double-sided screen printing prepared in Example 2 is as follows: Figure 8 As shown in the figure, when the temperature difference between the hot and cold ends of the three-dimensional thermoelectric device increases from 0°C to 50°C, the open circuit voltage increases from 0mV to 725mV. 2 / r, where U is the open circuit voltage of the three-dimensional thermoelectric device and r is the measured internal resistance of the three-dimensional thermoelectric device. It can be seen that its power increases from 0 to 120μW. Since the volume of the three-dimensional thermoelectric device is 2.2425cm 3 , and then the power density of the three-dimensional thermoelectric device is calculated to be 53.5μW / cm 3 It can be seen that the three-dimensional thermoelectric device based on double-sided screen printing prepared in Example 2 has the advantages of high output power density, compact structure, high integration and small occupied area.

[0083] Example 4

[0084] This embodiment provides another method for preparing the three-dimensional thermoelectric device based on double-sided screen printing described in Embodiment 1. Compared with Embodiment 2, the only difference is that the multiple folding technology in step 10 is adjusted as follows: Fig. 9 As shown, specifically:

[0085] First, the gaps between adjacent rows in the two-dimensional layout structure are partially cut to ensure that the adjacent rows are connected end to end; then, starting from the first row, the thermoelectric units are folded in different directions in sequence with the midline of the top electrode unit as the crease to form a three-dimensional layered structure unit; the three-dimensional layered structure unit of the first row is folded to the second row, and the thermoelectric units of the second row are folded in different directions in sequence until all rows of thermoelectric units are folded in sequence to form a three-dimensional layered structure;

[0086] The other preparation processes are exactly the same.

[0087] Compared with Example 2, the hot end and cold end of each layer of the thermoelectric unit in the three-dimensional thermoelectric device based on double-sided screen printing obtained in this embodiment can be directly in contact with the environment, avoiding heat loss through the substrate, increasing the temperature difference between the two ends of the thermoelectric unit, and thereby improving the output of the thermoelectric device.

[0088] The above embodiments only illustrate the principles and advantages of the present invention, and are not intended to limit the present invention. They are only intended to help understand the principles of the present invention. The protection scope of the present invention is not limited to the above configurations and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the disclosed technology without departing from the essence of the present invention, but they are still within the protection scope of the present invention.

Claims

1. A three-dimensional thermoelectric device based on double-sided screen printing, It is characterized in that The two-dimensional layout structure is obtained by folding the two-dimensional layout structure multiple times; the two-dimensional layout structure is a double-sided structure prepared by a screen printing process on a substrate, the structures of the two sides are the same, and each side structure includes a bottom electrode layer, an N-type thermoelectric material layer, a P-type thermoelectric material layer and a top electrode layer in sequence; The bottom electrode layer is an array consisting of 4m×2n isolated bottom electrode units; the N-type thermoelectric material layer is an array consisting of m×n isolated N-type thermoelectric legs; The P-type thermoelectric material layer is an array of m×n isolated P-type thermoelectric legs; the top electrode layer is an array of (2m+1)×2n isolated top electrode units; The N-type thermoelectric legs and the P-type thermoelectric legs are alternately arranged to form a 2m×2n double-grid structure array; in each row of the double-grid structure array, the two sides of the N-type thermoelectric legs have overlapping regions with two bottom electrode units respectively, and the two sides of the P-type thermoelectric legs have overlapping regions with two bottom electrode units respectively, and the top electrode unit is located in the area between the adjacent N-type thermoelectric legs and the P-type thermoelectric legs, and has an overlapping region with the N-type thermoelectric legs and the P-type thermoelectric legs, and has an overlapping region with the bottom electrode unit overlapping one side of the N-type thermoelectric legs, and has an overlapping region with the bottom electrode unit overlapping one side of the P-type thermoelectric legs, so that the adjacent N-type thermoelectric legs and P-type thermoelectric legs in each row are electrically interconnected; The top electrode units in adjacent rows in the top electrode layer are connected end to end to form an electrical interconnection region of a serpentine bending structure in each side structure; By folding multiple times, the two-dimensional layout structure is folded into a three-dimensional thermoelectric device formed by stacking 2m×2n layers of thermoelectric units, and each layer of thermoelectric units includes an N-type thermoelectric leg or a P-type thermoelectric leg.

2. According to claim 1, the three-dimensional thermoelectric device based on double-sided screen printing, It is characterized in that The substrate is a polyimide film with a thickness of 15 to 50 μm; the materials of the bottom electrode layer and the top electrode layer are silver.

3. According to the three-dimensional thermoelectric device based on double-sided screen printing as claimed in claim 2, It is characterized in that The electrical interconnection of the double-sided structure is achieved by providing through holes in the top electrode layer.

4. According to claim 3, the three-dimensional thermoelectric device based on double-sided screen printing, It is characterized in that During the multiple folding process, polyimide films are introduced to insulate adjacent layers of thermoelectric units.

5. The three-dimensional thermoelectric device based on double-sided screen printing according to any one of claims 1 to 4, It is characterized in that By changing the area of ​​the overlapping region between the N-type thermoelectric leg and the bottom electrode unit, as well as the area of ​​the overlapping region between the P-type thermoelectric leg and the bottom electrode unit, the contact resistance between the bottom electrode layer and the N-type thermoelectric material layer and the P-type thermoelectric material layer is adjusted, thereby adjusting the internal resistance of the three-dimensional thermoelectric device.

6. A method for preparing a three-dimensional thermoelectric device based on double-sided screen printing, It is characterized in that The following steps are involved: Step 1, preparing a thermoelectric ink base liquid, and preparing an N-type thermoelectric ink and a P-type thermoelectric ink based on the thermoelectric ink base liquid; Step 2, pre-drilling through holes on the substrate; Step 3: placing screens with bottom electrode unit patterns on both sides of the substrate, and printing conductive silver paste on both sides of the substrate using a screen printing process, and obtaining a bottom electrode layer after pre-curing; Step 4: Place a screen with a P-type thermoelectric leg pattern on both sides of the substrate treated in step 3, and use a screen printing process to print a P-type thermoelectric ink on the bottom electrode layer, and obtain a P-type thermoelectric material layer after pre-curing; Step 5, placing screens with N-type thermoelectric leg patterns on both sides of the substrate treated in step 4, and printing N-type thermoelectric ink on the bottom electrode layer using a screen printing process, and obtaining an N-type thermoelectric material layer after pre-curing; Step 6, heat-treating the substrate processed in step 5, and then placing screens with top electrode unit patterns on both sides of the substrate, and printing stretchable silver paste on both sides of the substrate using a screen printing process, and obtaining a top electrode layer after pre-curing, thereby obtaining a two-dimensional layout structure; Step 7: Partially encapsulate the two-dimensional layout structure with a base material, and fold the encapsulated two-dimensional layout structure into a three-dimensional layered structure through multiple folding, thereby obtaining the three-dimensional thermoelectric device based on double-sided screen printing as described in claim 4.

7. The method for preparing a three-dimensional thermoelectric device based on double-sided screen printing according to claim 6, It is characterized in that A specific process of the multiple folding is: First, the gaps between adjacent rows in the two-dimensional layout structure are used as creases, and each row is folded in the same direction to form a long strip structure; then, the midline of the top electrode unit in the long strip structure is used as a crease, and each thermoelectric unit is folded in different directions to form a three-dimensional layered structure.

8. The method for preparing a three-dimensional thermoelectric device based on double-sided screen printing according to claim 6, It is characterized in that Another specific process of the multiple folding is: First, the gaps between adjacent rows in the two-dimensional layout structure are partially cut to ensure that the adjacent rows are connected end to end; then, starting from the first row, each thermoelectric unit is folded in half in different directions with the midline of the top electrode unit as the crease to form a three-dimensional layered structure unit; the three-dimensional layered structure unit of the first row is folded to the second row, and the thermoelectric units of the second row are folded in half in different directions until all rows of thermoelectric units are folded in half to form a three-dimensional layered structure.

9. The method for preparing a three-dimensional thermoelectric device based on double-sided screen printing according to claim 6, It is characterized in that The three-dimensional thermoelectric device includes a hot end and a cold end. Specifically, the fold of the top electrode unit on the same side of each layer of thermoelectric units is the hot end, and the fold of the top electrode unit on the opposite side is the cold end.

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